Bottom Line:
Here, disruption of the desE gene in S. coelicolor, and subsequent phenotypic analysis, is used to demonstrate a link between iron metabolism and physiological and morphological development.Streptomyces coelicolor desE mutants, isolated in both wild-type (M145) and a coelichelin biosynthesis and transport minus background (mutant W3), a second hydroxamate siderophore system only found in S. coelicolor and related species, resulted in impaired growth and lack of sporulation.The biotechnological and ecological implications of these observations are discussed.

f4: Complementation of the desE mutant V3 with desE and cdtB. Growth curves of V3desE, V3cdtB, and the empty vector strain V3pIJ6902, grown at 30°C in liquid YEME supplemented with 2,2′‐dipyridyl (200 µM) and apramycin (50 µg ml−1). The inset picture shows the corresponding phenotypes of all three strains grown in R2YE agar plates, without 2,2′‐dipyridyl, and incubated at 30°C. The pictures were taken after 2 (top half, 48 h) and 5 days (bottom half, 120 h).

Mentions:
Impaired growth of the desE mutant V3 was also recorded in YEME liquid medium supplemented with 200 µM 2,2′‐dipyridyl. At this concentration, as can be seen in Fig. 4, the mutant V3 transformed with the chromosomally integrating PtipA empty expression vector pIJ6902, i.e. strain V3pIJ6902, has an extended lag phase of around 50 h. This situation is reversed when V3 is transformed with pIJ6902 constructs containing either desE and cdtB genes, under the control of the PtipA promoter, even without induction of expression with thiostrepton (Fig. 4). However, the phenotypes of the complemented strains, called V3desE and V3cdtB, were only partially rescued on solid R2YE medium supplemented with the iron‐chelator at the same concentration. Sporulation was not fully recovered (Fig. 4) and unexpectedly, the increased restoration of sporulation was obtained with pIJ6902cdtB, rather than with pIJ6902desE. Indeed, in both solid and liquid iron‐limited media V3cdtB grows better than V3desE, and produces more actinorhodin, as judged by visual inspection.

f4: Complementation of the desE mutant V3 with desE and cdtB. Growth curves of V3desE, V3cdtB, and the empty vector strain V3pIJ6902, grown at 30°C in liquid YEME supplemented with 2,2′‐dipyridyl (200 µM) and apramycin (50 µg ml−1). The inset picture shows the corresponding phenotypes of all three strains grown in R2YE agar plates, without 2,2′‐dipyridyl, and incubated at 30°C. The pictures were taken after 2 (top half, 48 h) and 5 days (bottom half, 120 h).

Mentions:
Impaired growth of the desE mutant V3 was also recorded in YEME liquid medium supplemented with 200 µM 2,2′‐dipyridyl. At this concentration, as can be seen in Fig. 4, the mutant V3 transformed with the chromosomally integrating PtipA empty expression vector pIJ6902, i.e. strain V3pIJ6902, has an extended lag phase of around 50 h. This situation is reversed when V3 is transformed with pIJ6902 constructs containing either desE and cdtB genes, under the control of the PtipA promoter, even without induction of expression with thiostrepton (Fig. 4). However, the phenotypes of the complemented strains, called V3desE and V3cdtB, were only partially rescued on solid R2YE medium supplemented with the iron‐chelator at the same concentration. Sporulation was not fully recovered (Fig. 4) and unexpectedly, the increased restoration of sporulation was obtained with pIJ6902cdtB, rather than with pIJ6902desE. Indeed, in both solid and liquid iron‐limited media V3cdtB grows better than V3desE, and produces more actinorhodin, as judged by visual inspection.

Bottom Line:
Here, disruption of the desE gene in S. coelicolor, and subsequent phenotypic analysis, is used to demonstrate a link between iron metabolism and physiological and morphological development.Streptomyces coelicolor desE mutants, isolated in both wild-type (M145) and a coelichelin biosynthesis and transport minus background (mutant W3), a second hydroxamate siderophore system only found in S. coelicolor and related species, resulted in impaired growth and lack of sporulation.The biotechnological and ecological implications of these observations are discussed.